A method of this kind and an electric circuit of this kind are known, for example, from DE 10 2007 014 728 A1. The stator current flowing to the stator and the rotor current flowing to the rotor are measured by means of sensors and then taken into account in the open-loop and/or closed-loop control of the circuit.
In case of a fault in the power grid, in particular after a collapse in the mains voltage, the measurement of the stator current can be inaccurate or even incorrect. The open-loop and/or closed-loop control of the circuit can thus lead to considerable control errors and thus potentially cannot be continued on the basis of the stator current.